Вільна конвекція — дослідження регулярного теплового режиму в різних шарах по висоті рідини

Abstract

The rate of cooling (heating) of experimental liquids is investigated separately for five thermocouples located at different heights of the experimental probe. Research is carried out on an experimental stand in the system "environment I — body II", where "environment I" is water, and "body II" is the investigated liquid medium in a thin metal cylindrical shell under conditions of free convection. The rate of cooling (heating) is studied for test liquids: water, sunflower oil, distilled glycerin. The analysis of cooling (heating) processes during free convection of non-stationary heat exchange is carried out. This paper presents research carried out on an experimental stand, which consists of an external metal vessel, containing the environment with a temperature of t1, an internal cylindrical metal vessel containing an experimental liquid medium with a temperature of t2. Accordingly, probes with five thermocouples are placed in hot and cold liquids to take temperature values at a fixed time Non-stationary heat conduction processes occur during heating or cooling of bodies, substances, gaseous media and are accompanied by a change in enthalpy. Non-stationary and stationary processes of body heating due to the internal heat source, the electric heater, are considered in laboratory practice to determine the thermophysical properties of materials, bodies of substances and where cooling occurs due to the surrounding air. The analysis of the excess temperature, carried out separately for each thermocouple, placed along the height of the cylindrical volume, shows that the linearity of the dependence Ln ϑ = f(τ) is preserved, while the influence of free convection on the value of m is manifested. The value of m depends on the height of the liquid layer in which the temperature is measured.